Patent GB-849524-A (GB)
Title: Improvements in or relating to size controlling device for internal grinding machines
IPC: B24B49/04
Filed: 1957-01-18
Abstract: 849,524. Pneumatic, gauging-apparatus. ULVSUNDA VERKSTADER A.B. Jan. 18, 1957 [Jan. 19, 1956], No. 1930/57. Class 106 (2). [Also in Group XXIII] In an internal grinding machine in which the workpiece 24, Figs. 1 and 2, and grinding wheel 34 are rotated and, at the same time, moved in a transverse direction relative to one another for successive grinding of an internal surface of revolution 38, a pneumatic size-controlling device comprises a part 56 provided with at least one nozzle 80 for the discharge of a pressure medium, the part being of such a shape as to enable it to lie within the workpiece adjacent the grinding wheel and remain within the workpiece during the grinding operation. As shown, two nozzles 80 are positioned at diametrically opposed points relative to the workpiece in the crescent-shaped part 56 which is secured to a disc 54 clamped by a member 52 to a non- rotatable but axially movable rod 40 passing through a spindle 14 mounted for rotation in bearings 12 in the machine head 10. Each nozzle is provided with a groove 78 on the external surface of the part 56 to lead away the air which is supplied under pressure through bores 48, 64, 66 in the rod, disc and part 56, and a channel 72 on the inner surface of the part 56 enclosed by a thin strip of sheet metal 74. In operation, the workpiece 24 is held by jaws 22 in a chuck 16 attached to the spindle and the device and grinding wheel axially moved by known means on to the workpiece. The grinding wheel, which is axially longer than the workpiece, is reciprocated and radially fed into the surface to be ground. As the diameter of the internal surfaces increases, the space between the nozzles 80 and the surface 38 also increases, reducing the resistance to the outlet of air from the nozzles and decreasing the pressure in the bores 48, 64, 66. When the pressure drops to a predetermined value based on the required finished size, a differential pressure gauge, connected in the pneumatic circuit, actuates operating members to withdraw the grinding wheel from the workpiece. An embodiment for use in grinding workpieces of larger size has a portion 92, Fig. 5, secured to the axially outer end of the part 56. The portion 92 is of less diameter than the part 56 and has a nozzle 94, midway of the arc of part 56, connected by bores 96, 98, 100 to a separate air supply and differential pressure gauge. Only the portion 92 with the nozzle 94 is inserted into the workpiece during the roughing operation until, when the surface is nearly to size, its differential pressure gauge actuates members to move the part 56 with the nozzles 80 into the workpiece for the finishing operation. One or more nozzles 84 connected by a bore 82 to a further separate air supply may be provided to remove water and detached particles from the inner surface 38 of the workpiece. In a further embodiment the nozzles 80 are located on arms which are slidably mounted in radial T or dovetailed grooves in the disc 54 and are adjustably secured to accommodate different diameters of workpieces. The rate of feed of the grinding wheel may be controlled by resistances or valves varied by the changes of pressure in the differential pressure gauges.